This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Problems of AM”.
1. If the modulating frequency of a carrier wave varies between 700Hz and 7KHz, find it’s bandwidth?
a) 10 KHz
b) 23 KHz
c) 17.3 KHz
d) 12.6 KHz
Explanation: fm= 7KHz – 700Hz =6.3KHz and Bandwidth = 2fm= 2 x 6.3 = 12.6 KHz.
2. A 400W carrier wave is modulated to a depth of 65%. Find the total power of modulated wave?
Explanation: Pt = Pc (1 + m2⁄2). By putting values in the equation we have Pt = 400 (1 +0.652⁄2) = 484.5W.
3. Inductance and capacitance of a line is 0.8 μH⁄m and 32 pF⁄m . Find Z0 )?
4. Find VSWR of a line having maximum and minimum value equals to 120mV and 40mV respectively?
5. A 1000 KHz carrier is modulated with 300 Hz, 8000 Hz and 2 KHz waves. Determine the frequencies whose chances of occurring in output is least?
a) 1000 KHz
b) 1002 KHz
c) 998 KHz
d) 999.2 KHz
Explanation: Frequencies present in output are of the form fc ± fm, fc ± 2fm, fc ± 3fm.
6. If average power of a transmitter is 4kW and maximum power is 20000KW. What is its duty cycle?
a) 2 x 10-3
b) 2 x 10-4
c) 3 x 10-3
7. The voltage and electric current of a line are respectively 5kV and 1000μA. Find its power?
Explanation: Power, P =V x I. By substituting the values of voltage(V) and current(I), we have P = (5×103)(1000×10-6) = 5W
8. ________ microphones works on piezoelectric effect?
c) Moving coil
Explanation: Piezoelectric effect is the ability of materials to generate an electric charge in response to applied mechanical stress. Crystal microphones works on the piezoelectric effect.
9. If modulation index of an AM wave is increased from 1.5 to 2, then the transitted power ________
a) remains same
b) increases by 20%
c) increases by 41%
d) increases by 50%
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.